Magnetic resonance neurography of the pelvis and lumbosacral plexus

Recent advances in magnetic resonance (MR) imaging have revolutionized peripheral nerve imaging and made high-resolution acquisitions a clinical reality. High-resolution dedicated MR neurography techniques can show pathologic changes within the peripheral nerves as well as elucidate the underlying disorder or cause. Neurogenic pain arising from the nerves of the pelvis and lumbosacral plexus poses a particular diagnostic challenge for the clinician and radiologist alike. This article reviews the advances in MR imaging that have allowed state-of-the-art high-resolution imaging to become a reality in clinical practice.

Use of motor evoked potentials during lateral lumbar interbody fusion reduces postoperative deficits

BACKGROUND CONTEXT

Intraoperative neurophysiological monitoring (IONM) has gained rather widespread acceptance as a method to mitigate risk to the lumbar plexus during lateral lumbar interbody fusion (LLIF) surgery. The most common approach to IONM involves using only electromyography (EMG) monitoring, and the rate of postoperative deficit remains unacceptably high. Other test modalities, such as transcranial electric motor-evoked potentials (tcMEPs) and somatosensory-evoked potentials, may be more suitable for monitoring neural integrity, but they have not been widely adopted during LLIF. Recent studies have begun to examine their utility in monitoring LLIF surgery with favorable results.

PURPOSE

This study aimed to evaluate the efficacy of different IONM paradigms in the prevention of iatrogenic neurologic sequelae during LLIF and to specifically evaluate the utility of including tcMEPs in an IONM strategy for LLIF surgery.

STUDY DESIGN/SETTING

A non-randomized, retrospective analysis of 479 LLIF procedures at a single institution over a 4-year period was conducted. During the study epoch, three different IONM strategies were used for LLIF procedures: (1) surgeon-directed T-EMG monitoring ("SD-EMG"), (2) neurophysiologist-controlled T-EMG monitoring ("NC-EMG"), and (3) neurophysiologist-controlled T-EMG monitoring supplemented with MEP monitoring ("NC-MEP").

PATIENT SAMPLE

The patient population comprised 254 men (53.5%) and 221 women (46.5%). Patient age ranged from a minimum of 21 years to a maximum of 89 years, with a mean of 56.6 years.

OUTCOME MEASURES

Physician-documented physiological measures included manual muscle test grading of hip-flexion, hip-adduction, or knee-extension, as well as hypo- or hyperesthesia of the groin or anterolateral thigh on the surgical side. Self-reported measures included numbness or tingling in the groin or anterolateral thigh on the surgical side.

METHODS

Patient progress notes were reviewed from the postoperative period up to 12 months after surgery. The rates of postoperative sensory-motor deficit consistent with lumbar plexopathy or peripheral nerve palsy on the surgical side were compared between the three cohorts.

RESULTS

Using the dependent measure of neurologic deficit, whether motor or sensory, patients with NC-MEP monitoring had the lowest rate of immediate postoperative deficit (22.3%) compared with NC-EMG monitoring (37.1%) and SD-EMG monitoring (40.4%). This result extended to sensory deficits consistent with lumbar plexopathy (pure motor deficits being excluded); patients with NC-MEP monitoring had the lowest rate (20.5%) compared with NC-EMG monitoring (34.3%) and SD-EMG monitoring (36.9%). Additionally, evaluation of postoperative motor deficits consistent with peripheral nerve palsy (pure sensory deficits being excluded) revealed that the NC-MEP group had the lowest rate (5.7%) of motor deficit compared with the SD-EMG (17.0%) and NC-EMG (17.1%) cohorts. Finally, when assessing only those patients whose last follow-up was greater than or equal to 12 months (n=251), the rate of unresolved motor deficits was significantly lower in the NC-MEP group (0.9%) compared with NC-EMG (6.9%) and SD-EMG (11.0%). A comparison of the NC-MEP versus NC-EMG and SD-EMG groups, both independently and combined, was statistically significant (>95% confidence level) for all analyses.

CONCLUSIONS

The results of the present study indicate that preservation of tcMEPs from the adductor longus, quadriceps, and tibialis anterior muscles are of paramount importance for limiting iatrogenic sensory and motor injuries during LLIF surgery. In this regard, the inclusion of tcMEPs serves to compliment EMG and allows for the periodic, functional assessment of at-risk nerves during these procedures. Thus, tcMEPs appear to be the most effective modality for the prevention of both transient and permanent neurologic injury during LLIF surgery. We propose that the standard paradigm for protecting the nervous system during LLIF be adapted to include tcMEPs.

Femoral nerve and lumbar plexus injury after minimally invasive lateral retroperitoneal transpsoas approach: electrodiagnostic prognostic indicators and a roadmap to recovery

Injury to the lumbosacral (LS) plexus is a well-described complication after lateral retroperitoneal transpsoas approaches to the spine. The prognosis for functional recovery after lumbosacral plexopathy or femoral/obturator neuropathy is unclear. We designed a retrospective case-control study with patients undergoing one-level lateral retroperitoneal transpsoas lumbar interbody fusion (LLIF) between January 2011 and June 2016 to correlate electrodiagnostic assessments (EDX) to physiologic concepts of nerve injury and reinnervation, and attempt to build a timeline for patient evaluation and recovery. Cases with post-operative obturator or femoral neuropathy were identified. Post-operative MRI, nerve conduction studies (NCS), electromyography (EMG), and physical examinations were performed at intervals to assess clinical and electrophysiologic recovery of function. Two hundred thirty patients underwent LLIF. Six patients (2.6%) suffered severe femoral or femoral/obturator neuropathy. Five patients (2.2%) had immediate post-operative weakness. One of the six patients developed delayed weakness due to a retroperitoneal hematoma. Five out of six patients (83%) demonstrated EDX findings at 6 weeks consistent with axonotmesis. All patients improved to at least MRC 4/5 within 12 months of injury. In conclusion, neurapraxia is the most common LS plexus injury, and complete recovery is expected after 3 months. Most severe nerve injuries are a combination of neurapraxia and variable degrees of axonotmesis. EDX performed at 6 weeks and 3, 6, and 9 months provides prognostic information for recovery. In severe injuries of proximal femoral and obturator nerves, observation of proximal to distal progression of small-amplitude, short-duration (SASD) motor unit potentials may be the most significant prognostic indicator.

Regional anesthesia for orthopedic procedures: What orthopedic surgeons need to know

Regional anesthesia is an integral component of successful orthopedic surgery. Neuraxial anesthesia is commonly used for surgical anesthesia while peripheral nerve blocks are often used for postoperative analgesia. Patient evaluation for regional anesthesia should include neurological, pulmonary, cardiovascular, and hematological assessments. Neuraxial blocks include spinal, epidural, and combined spinal epidural. Upper extremity peripheral nerve blocks include interscalene, supraclavicular, infraclavicular, and axillary. Lower extremity peripheral nerve blocks include femoral nerve block, saphenous nerve block, sciatic nerve block, iPACK block, ankle block and lumbar plexus block. The choice of regional anesthesia is a unanimous decision made by the surgeon, the anesthesiologist, and the patient based on a risk-benefit assessment. The choice of the regional block depends on patient cooperation, patient positing, operative structures, operative manipulation, tourniquet use and the impact of post-operative motor blockade on initiation of physical therapy. Regional anesthesia is safe but has an inherent risk of failure and a relatively low incidence of complications such as local anesthetic systemic toxicity (LAST), nerve injury, falls, hematoma, infection and allergic reactions. Ultrasound should be used for regional anesthesia procedures to improve the efficacy and minimize complications. LAST treatment guidelines and rescue medications (intralipid) should be readily available during the regional anesthesia administration.

Trans-cranial motor evoked potential detection of femoral nerve injury in trans-psoas lateral lumbar interbody fusion

Trans-psoas lateral lumbar interbody fusion (LLIF) is frequently associated with neurological complications, limiting its value as a less invasive procedure. The routine use of EMG neuromonitoring has been inadequate to detect iatrogenic injuries; significant postoperative deficits have gone undetected by EMG. An effective way to monitor for these intraoperative neurological events is not yet well established. To our knowledge, detection of lumbar plexus injury during LLIF by trans-cranial motor evoked potentials (MEP) without corresponding change in EMG has not been reported in the literature. Three cases are presented to illustrate the potential utility of trans-cranial MEP monitoring during trans-psoas LLIF. We introduce a modified intraoperative neuro-monitoring (IONM) protocol for LLIF surgery, which includes MEP in addition to spontaneous and triggered EMG. Postoperative neurological outcome was correlated with the IONM findings. In each case, loss of quadriceps MEP signals occurred during LLIF at L4/L5, and after prolonged retraction (27, 25 and 61 min respectively). The EMG, however, did not show any abnormal activity. Two patients had post-operative quadriceps weakness, concordant with MEP data. The third patient, in whom the MEP signals returned to normal after expeditious removal of the retractor, did not exhibit quadriceps weakness, also concordant with MEP data. These cases contribute to the developing perception that stand-alone EMG nerve monitoring is not adequate for trans-psoas surgery. The addition of MEP may improve the sensitivity of IONM during trans-psoas surgery. Multimodality IONM may offer the opportunity to intervene on evolving iatrogenic nerve injuries, and may reduce the incidence of adverse postoperative findings.

3.0T MRI tractography of lumbar nerve roots in disc herniation

BACKGROUND

Diffusion tensor imaging (DTI) with fiber tracking (FT) has found clinical applications in the evaluation of the central nervous system and has been extensively used to image white matter tract. The feasibility of FT of the lumbar nerve roots in disc herniation is unclear.

PURPOSE

To demonstrate the feasibility of FT in the lumbar nerve roots, and to assess potential differences in fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of L4, L5, and S1 nerves between healthy disc and disc herniation.

MATERIAL AND METHODS

Twenty patients with unilateral sciatica related to posterolateral or foraminal disc herniation and 20 healthy volunteers were enrolled in our study. Anatomical fusion with the axial T2 sequences was used to estimate the relevance of reconstructions. DTI with tractography of the L4, L5, and S1 nerves was performed. Mean FA and ADC values were calculated from tractography images.

RESULTS

Lumbosacral root compression sites could be clearly identified on the tractography images. There was no significant difference in FA or ADC between left and right nerve roots at the same level (P > 0.05) in healthy volunteers. The mean FA value of the compressed spinal nerve roots was significantly lower than that of FA of the contralateral nerve roots (P = 0.0001). ADC was significantly higher in compressed nerve roots than that in the contralateral nerve root (P = 0.0002).

CONCLUSION

3 T magnetic resonance imaging (MRI) DTI and FT of the lumbosacral region nerve is possible. There are significant changes in FA and ADC values in the compressed L4, L5, and S1 nerves.

Effect of continuous psoas compartment block and intravenous patient controlled analgesia on postoperative pain control after total knee arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) generates severe postoperative pain in 60% of patients and moderate pain in 30% of patients. Because inadequate postoperative pain control can hinder early physiotherapy and rehabilitation, it is the most influential factor dictating a good outcome. The purpose of this study was to evaluate the effectiveness of continuous psoas compartment block (PCB) in comparison to intravenous patient-controlled analgesia (IVPCA) in TKA patients.

METHODS

40 TKA patients were randomly divided into 2 groups. Group IVPCA (n = 20) received intravenous patient controlled analgesia (IVPCA) for 48 hours. Group PCB (n = 20) received continuous PCB for 48 hours at the fourth intertransverse process of the lumbar using the C-arm. Pain scores, side effects, satisfaction, the length of hospital stay, rescue antiemetics, and analgesics were recorded.

RESULTS

Pain scores (VNRS 0-100) were higher in Group IVPCA than in Group PCB. Nausea and sedation occurred more frequently in Group IVPCA than in Group PCB. There were no differences between the groups in the length of the hospital stay, satisfaction scores, and the use of rescue antiemetics and analgesics.

CONCLUSIONS

Continuous PCB seemed to be an appropriate and reliable technique for TKA patients, because it provided better analgesia and fewer side effects such as nausea and sedation when compared to IVPCA.

A MRI study of lumbar plexus with respect to the lateral transpsoas approach to the lumbar spine

PURPOSE

To evaluate the relative position between lumbar plexus and access corridor of minimally invasive lateral transpsoas lumbar approach, as well as the approach safety.

METHODS

Three-dimensional fast imaging employing steady-state acquisition (3D FIESTA) sequence images of lumbar spine were obtained from 58 patients with lumbar degenerative diseases for reconstruction to analyze the distribution of lumbar plexus from L1-L2 to L4-L5 level with respect to the transpsoas lumbar approach. The axial image distance (AID) between the anterior edge of lumbar plexus and the sagittal central perpendicular line (SCPL) of disc was measured. SCPL was drawn perpendicularly to the sagittal plane of intervertebral disc and it passed through its central point, which is initial dilator trajectory for transpsoas approach. As related to the SCPL of disc, the distance with a positive value was set to indicate neural tissue posterior to it, while anterior to it was represented by a negative value.

RESULTS

In relation to SCPL of disc, the AID of lumbar plexus was measured 13.01 ± 1.70, 8.61 ± 2.26, 1.12 ± 2.37 and -5.42 ± 3.26 mm from L1-L2 to L4-L5 level, respectively, while the AID of genitofemoral nerve was recorded -1.13 ± 2.87, -5.78 ± 2.33 and -10.53 ± 3.30 mm from L2-L3 to L4-L5 level accordingly.

CONCLUSION

With respect to the SCPL of disc, a trajectory of guide wire or a radiographic reference landmark to place working channel, lumbar plexus lies posteriorly to it from L1-L2 to L3-L4 level and shifts anteriorly to it at L4-L5 level, while genitofemoral nerve locates anteriorly to the SCPL from L2-L3 to L4-L5 level. Neural retraction may take place during sequential dilation of access corridor especially at L4-L5 level.

Saphenous somatosensory-evoked potentials monitoring of femoral nerve health during prone transpsoas lateral lumbar interbody fusion

PURPOSE

To assess whether saphenous somatosensory-evoked potentials (saphSSEP) monitoring may provide predictive information of femoral nerve health during prone lateral interbody fusion (LIF) procedures.

METHODS

Intraoperative details were captured prospectively in consecutive prone LIF surgeries at a single institution. Triggered electromyography was used during the approach; saphSSEP was monitored throughout using a novel system that enables acquisition of difficult signals and real-time actionable feedback facilitating intraoperative intervention. Postoperative neural function was correlated with intraoperative findings.

RESULTS

Fifty-nine patients (58% female, mean age 64, mean BMI 32) underwent LIF at 95 total levels, inclusive of L4-5 in 76%, fixated via percutaneous pedicle screws (81%) or lateral plate, with direct decompression in 39%. Total operative time averaged 149 min. Psoas retraction time averaged 16 min/level. Baseline SSEPs were unreliable in 3 due to comorbidities in 2 and anesthesia in 1; one of those resulted in transient quadriceps weakness, fully recovered at 6 weeks. In 25/56, no saphSSEP changes occurred, and none had postoperative femoral nerve deficits. In 24/31 with saphSSEP changes, responses recovered intraoperatively following intervention, with normal postoperative function in all but one with delayed quadriceps weakness, improved at 4 months and recovered at 9 months, and a second with transient isolated anterior thigh numbness. In the remaining 7/31, saphSSEP changes persisted to close, and resulted in 2 transient isolated anterior thigh numbness and 2 combined sensory and motor femoral nerve deficits, both resolved at between 4 and 8 months.

CONCLUSIONS

SaphSSEP was reliably monitored in most cases and provided actionable feedback that was highly predictive of neurological events during LIF.

LEVEL OF EVIDENCE

Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Ultrasound-guided lumbar plexus block using three different techniques: a comparison of ultrasound image quality

PURPOSE

The purpose of this study was to compare the ultrasound image quality at three different transducer positions for ultrasound-guided lumbar plexus block (LPB).

METHODS

This prospective comparative study included 30 patients who underwent total hip arthroplasty under general anesthesia in combination with LPB. Using the same ultrasound machine settings for each patient, a transverse view of the lumbar plexus (LP) at the L3-4 vertebral level was obtained with a convex transducer placed at three different positions: immediately lateral to the dorsal midline (medial position), almost 5 cm lateral to the dorsal midline (paravertebral position), and at the abdominal transverse flank (shamrock position). Ultrasound-guided LPB with catheter insertion was performed via in-plane needle insertion with the transducer randomly assigned to one of the three positions. The echo intensity (EI) ratio of the LP to psoas major muscle (PMM), the EI of the LP and PMM, and the ultrasound visibility score of the needle, local anesthetic, and catheter were recorded.

RESULTS

The LP/PMM EI ratio was significantly higher at paravertebral position (1.4 ± 0.2) than at medial position (1.2 ± 0.2; p = 0.003) and shamrock position (1.3 ± 0.2; p = 0.040). The EI of the LP and PMM was highest at shamrock position (p < 0.001). During the block procedure, the ultrasound visibility score of the needle and local anesthetic was significantly higher at paravertebral position than at medial position.

CONCLUSION

Under the conditions of this study, the contrast between LP and PMM is significantly higher at paravertebral position than at medial position and at the abdominal transverse flank (shamrock position). LP and PMM at the shamrock position appear significantly brighter among the three probe positions in sonograms.

Inguinal segmental nerve conduction of the lateral femoral cutaneous nerve in healthy controls and in patients with meralgia paresthetica

A common entrapment site of the lateral femoral cutaneous nerve (LFCN) is in the vicinity of the inguinal ligament. However the more distal segment of this nerve can also be affected. Electrophysiological evaluation of this nerve is difficult. Additionally, available methods have failed in the lesion localization of LFCN. In this study, we aimed to evaluate nerve conduction study in different segments of the LFCN. Nerve action potentials of the LFCN were recorded with distal surface electrodes from a relatively distant point (about 30 cm caudal to the spina iliaca anterior superior). An electrical stimulus was given both 10 cm distal to the SIAS and at the level of the SIAS. Inguinal segmental and distal sensory nerve conduction studies were performed on the LFCN. Thirty-eight healthy controls and 34 patients with meralgia paresthetica (MP) were analyzed by this method. All patients with MP showed electrophysiological abnormalities. Slowed sensory conduction on the inguinal channel (p:0.0001) and loss of response were the most frequent abnormalities (44.7% and 31.6%). In one patient, the only abnormality was slowed sensory conduction at the distal site. Our findings suggest that this technique can help in diagnosis and lesion localization in MP.

Anatomic Study of the Bifurcation of the Obturator Nerve: Application to More Precise Surgical/Procedural Localization

BACKGROUND

This anatomic study aimed to more precisely locate the bifurcation of the obturator nerve in relationship to the obturator foramen. Such information might improve outcomes in neurotization or other procedures necessitating exposure of the obturator nerve and could increase success rates for obturator nerve blockade.

METHODS

Fourteen sides from fresh-frozen cadaveric specimens were used in this study. Dissection of the obturator nerve was performed, and its bifurcation into anterior and posterior branches was documented and classified. Measurements of these branches were also performed. Bifurcations of the obturator nerve were classified as type I when proximal to the obturator foramen, type II when inside the obturator foramen, and type III when distal to the obturator foramen.

RESULTS

Type I, type II, and type III obturator nerve bifurcations were observed in 14.3%, 64.3%, and 21.4% of sides, respectively. In type I nerves, the mean distance from the bifurcation of the obturator nerve to the obturator foramen was 15.8 mm, and in type II nerves the mean was 14.0 mm. The mean diameter of the main trunk, anterior branch, and posterior branch was 3.74 mm, 2.64 mm, and 2.28 mm, respectively.

CONCLUSIONS

Bifurcation of the obturator nerve can occur proximally, distally, or inside the obturator foramen. Therefore using imaging modalities such as ultrasound is strongly recommended for identifying the main trunk or anterior and posterior branches of the obturator nerve before surgery or other procedures aimed at this nerve due to such anatomic variations.

Novel Implementation of Extreme Lateral Interbody Fusion to Avoid Intraoperative Lumbar Plexus Injury: Technical Note and Preliminary Results

BACKGROUND

This study modified the traditional extreme lateral lumbar interbody fusion (XLIF) surgery and was intended to reduce the approach related to lumbar plexus injury.

METHODS

The patients receiving a new modified XLIF for treatment of lumbar degenerative diseases since September 2017 in our hospital were retrospectively collected. Postoperative additional symptoms of leg numbness, pain, or weakness were recorded as lumbar plexus nerve injury. Intraoperative electromyographic monitoring was recorded during surgery to evaluate the safety of the modified entry point. The visual analog scale and Oswestry Disability Index were adopted to evaluate the postoperative clinical efficacy. Modified MacNab criteria were introduced to evaluate the patients' satisfaction 12 months after surgery. The preoperative and postoperative intervertebral height, foraminal height, and lumbar lordotic angle were measured. Repeated measurement variance analysis was used for comparison of clinical and imaging indexes in various periods. P < 0.05 indicated statistical difference.

RESULTS

Fifty-nine patients were finally included in the retrospective study. The intraoperative average blood loss and operation time were 70 mL (40-130 mL) and 77.90 ± 13.65 minutes. The average follow-up time was 18 months. Postoperative visual analog scale and Oswestry Disability Index were significantly decreased compared with those before the operation. The intervertebral height and foraminal height were dramatically higher than those before surgery. No lumbar plexus injury occurred.

CONCLUSIONS

The initial result was optimistic in reducing lumbar plexus injury and obtaining good clinical efficacy. We need to further expand the sample size and carry out a comparative study to observe the advantages and disadvantages of modified XLIF.

[IMAGING STUDY ON LUMBAR PLEXUS BY MINIMALLY INVASIVE LATERAL TRANSPSOAS APPROACH]

OBJECTIVE

To analyze the relative position between lumbar plexus and access corridor of minimally invasive lateral transpsoas approach based on magnetic resonance imaging distribution of lumbar plexus by three dimensional reconstruction technique, so as to evaluate approach safety.

METHODS

Three-dimensional fast imaging employing steady-state acquisition sequences of lumbar spine were performed on 71 patients with lumbar degenerative diseases between July 2012 and January 2015. The axial image distance between the anterior edge of lumbar plexus and sagittal central perpendicular line (SCPL) of disc was determined using the distance formula at the mid-disc space from L_{1, 2} to L_{4, 5} level. SCPL was drawn perpendicularly to the sagittal plane of intervertebral disc and it passed through its central point, which is initial dilator trajectory for transpsoas approach. With respect to the SCPL of disc, the distance with a positive value indicated neural tissue posterior to it whereas anterior to it represented by a negative value.

RESULTS

Various branches of lumbar plexus which passed through the psoas major anterior to the SCPL of disc were identified in 42 (59.2%), 58 (81.7%), and 70 (98.6%) patients at L_{2, 3}, L_{3, 4}, and L_{4, 5} levels, respectively. It is possible to infer the presence of genitofemoral nerve in accordance with relevant anatomic research. A ventral migration of intrapsoas nerves is identified from L_{1, 2} to L_{4, 5} level. All differences between levels were statistically significant (P<0.05).

CONCLUSIONS

With respect to the SCPL of disc, a pass way of guide wire or a radiographic reference landmark to place working channel, lumbar plexus lie posterior to it from L_{1, 2} to L_{3, 4} level and shift anteriorly to it at L_{4, 5} level, while genitofemoral nerve locate anterior to the SCPL from L_{2, 3} to L_{4, 5} level. Neural retraction may take place during sequential dilation of working channel especially at L_{4, 5} level.

Effects of thigh extension on the position of the femoral nerve: application to prone lateral transpsoas approaches to the lumbar spine

Some authors have suggested that thigh extension during the prone lateral transpsoas approach to the lumbar spine provides the theoretical advantage of providing posterior shift of the psoas muscle and plexus and is responsible for its lower rates of nerve injury. We aimed to elucidate the effects of surgical positioning on the femoral nerve within the psoas muscle via a cadaveric study. In the supine position, 10 fresh frozen adult cadavers had a metal wire secured to the pelvic segment of the femoral nerve and then extended proximally along with its L2 contribution. Fluoroscopy was then used to identify the wires on the femoral nerves in a neutral position and with the thigh extended and flexed by 25 and 45°. Additionally, a lateral incision was made in the anterolateral abdominal wall to mimic a lateral transpsoas approach to the lumbar spine, and measurements were made of the amount of movement in the vertical plane of the femoral nerve from neutral to then 25 and 45° of thigh flexion and extension. On fluoroscopy, the femoral nerves moved posteriorly at a mean of 10.1 mm with thigh extension. Femoral nerve movement could not be detected at any degree of this range of flexion of the thigh. Extension of the thigh to about 30° can move the femoral nerve farther away from the dissection plane by approximately one centimeter. This hip extension not only places the femoral nerve in a more advantageous position for lateral lumbar interbody fusion procedures but also helps to promote accentuation of lumbar lordosis.

Analgesic efficacy of posterior and anterior psoas compartment block: Lumbar plexus versus three -in-one nerve block after lower limb orthopedic surgery under spinal anesthesia: A prospective cohort study

Introduction

Postoperative pain is the most common complaint in patients who underwent orthopedic surgery. Regarding with the severity of pain, orthopedic patients suffered more than non-orthopedic patients in the immediate post-operative period. Therefore, pain management is crucial for better patient outcome. Lumbar plexus (LB) and three -in-one (3IN1) nerve blocks have been routinely practiced as pain management techniques in the study area but the analgesic efficacy was not studied yet. Thus, this study was aimed to compare the analgesic efficacy of the LBP versus 3IN1B as postoperative pain management after thigh orthopedic surgery under spinal anesthesia.

Method

An institutional-based prospective cohort study was conducted from October 10, 2020 to March 30, 2021 at the University comprehensive specialized hospital. Non-probability convenient sampling was used to select participants in both groups. The time to first analgesic request, severity of pain and total analgesia consumption within the first postoperative 24 h were measured.

Result

The mean and standard deviation to seek the first analgesia request time was 11. 55 ± 2. 82hr and 13. 35 ± 2. 58hr (p- 0.07) in patients who received LPB and 3IN1B respectively. Pain severity at rest and on movement was also comparable. The total tramadol consumption was 67. 65 ± 27. 20 mg and 70. 59 ± 37. 19 mg (p- 0.71), while total Diclofenac consumption was 63. 23 ± 45. 74 mg and 44. 88 ± 34. 72 mg (p-0.07) in LPB and 3IN1B groups respectively.

Conclusion

The study showed that there was no significant difference in the time to first analgesia request, postoperative pain, both at rest and movement and total analgesic consumption, between the LPB and 3IN1B.

•

Orthopedic patients suffered more than non-orthopedic patients in the immediate post-operative period.

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Nerve blocks provide effective analgesic options.

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There are controversies comparing the efficacy of lumbar plexus and three in one femoral nerve block.

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Lumbar plexus and three in one nerve blocks have comparable time to seek 1st analgesia.

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Lumbar plexus and three in one nerve blocks have comparable pain severity and comparable analgesic consumption.

Postfixed lumbosacral plexus with split L5 ventral ramus and furcal nerve arising from L5

Variations of the peripheral nerve plexuses are important to those clinicians who diagnose and treat patients with pathology of their parts. During routine dissection, a postfixed lumbosacral plexus with a furcal nerve arising from L5, not L4, was discovered. In addition, the case was found to have a split L5 ventral ramus. Such a variation might become clinically significant during clinical presentations of radiculopathy. With a better understanding of the fucal nerve variation presented here, along with previously documented variations, the diagnostic and treatment procedures for atypical radiculopathy can be refined, reducing the rates of nerve injury and failed back surgery.

Use of test dose allows early detection of subdural local anesthetic injection with lumbar plexus block

A 56year-old woman underwent a lumbar plexus block for a revision of a left total hip arthroplasty. During the block procedure, the needle was advanced over the transverse process and isolated quadriceps twitches were elicited. After administering a test dose of 3ml of 1.5% lidocaine, the patient developed loss of sensation in the L3-4 dermatomal distribution that progressed caudally to involve both legs followed by inability to move the left leg. The patient shortly thereafter became hypotensive and sensory block spread cephalad and peaked at C7 bilaterally suggesting possible subdural spread of local anesthetic. The patient was resuscitated with normalization of blood pressure and eventually had full resolution of motor and sensory block. Subdural spread of local anesthetic is a potential complication of lumbar plexus block related perhaps to injection of local anesthetic near dural sleeves of nerve roots. The use of a test dose allows early recognition of subdural injection and may limit consequences of inadvertent subdural spread of local anesthetic.

Prominent caudal shift of the lumbar plexus roots in spines with 18 thoracolumbar vertebrae

PURPOSE

It remains unclear whether concomitant changes in the thoracolumbar (TL) vertebrae and lumbar plexus roots seen in experimental embryology are present in humans with different vertebral formulas, particularly in humans with 18 TL vertebrae. We thus investigated the human lumbar plexus root changes occurring in spines with an additional TL vertebra (18TL).

METHODS

The lumbosacral plexus was macroscopically dissected in TL anomaly cases found in 161 computed tomography examinations. TL anomalies were distinguished as simple abnormalities in total TL count and abnormal TL trade-offs, i.e., exchanges between the last thoracic and first lumbar vertebrae, and were analyzed separately.

RESULTS

One additional TL vertebra (7C_18TL_5S) was observed in 4/159 cases (2.5%), excluding cases with cervical and sacral abnormalities. Different from the unclear shifts of nerve roots in cases with 16TL and 17TL trade-offs, the 18TL trade-off tended to involve a caudal shift at the cranial limit, without event change at the caudal limit. In addition, only one nerve segment shift was reconfirmed with a change in two vertebral segments from 16 to 18 TL vertebrae.

CONCLUSIONS

We revealed that concomitant changes in the lumbar plexus roots and vertebrae in humans with 18TL vertebrae may become more pronounced than those in humans with 16 or 17TL vertebrae, by approaching the typical mammalian TL formula (19TL). This study showed that the TL formula can be used to estimate changes in the lumbar plexus roots, which may assist in the planning of nerve-sparing spinal and pelvic surgery.

Safe zone for irrigation and debridement of psoas abscess through a dorsal spinal approach

PURPOSE

This cadaver study was initiated to identify safe zones for psoas abscess debridement using a dorsal spinal approach.

METHODS

Twenty total specimens were dissected and lumbar transverse process (TP) and psoas muscles were identified. The distance from the lateral psoas muscle to the transverse process tip was measured. The lumbar plexus was dissected from the psoas and the distance from the TP to the lateral border of the lumbar plexus was measured. The area between the lateral edge of the psoas and lumbar plexus at each lumbar level was considered a safe zone of approach for entry into the psoas muscle for abscess debridement.

RESULTS

The most lateral portion of the lumbar plexus was 9.3 mm medial to the superior tip of the L1 TP and 9.2 mm medial to the inferior tip at L1, it was 11.8 and 11.7 mm medial at L2, 10.5 and 9.8 mm medial at L3, 6.6 and 6.2 mm medial at L4, and 1.0 and 0.9 mm medial at L5. The distances from the TP tip to the lateral edge of the psoas muscle were 5.7 and 5.5 mm medial to the superior and inferior tip of the TP at L1, 5.1 and 4.7 mm medial at L2, 2.5 and 1.8 mm medial at L3, 0.4 and 0 mm medial at L4 and 3.7 and 3.8 mm lateral at L5.

CONCLUSIONS

This study provides landmarks to avoid the critical structures in the lumbar spine.

[Choosing the right imaging for the diagnostics and assessment of the course of peripheral nerve injuries]

BACKGROUND

Nerve injuries are a frequent problem in routine clinical practice and require intensive interdisciplinary care.

OBJECTIVE

The current status of imaging to confirm the diagnosis of nerve injuries is described. The role of high-resolution ultrasound and magnetic resonance imaging (MRI) in the diagnostics and follow-up of peripheral nerve injuries is elaborated.

MATERIAL AND METHODS

Review of the current state of imaging to confirm the diagnosis of nerve injuries.

RESULTS

Depending on the suspected site of damage, the primary domain of magnetic resonance (MR) imaging (MR neurography) is injuries in the region of the spine, nerve roots, brachial plexus and lumbar plexus, pelvis and proximal thigh. In contrast, in other peripheral nerve lesions of the extremities the advantages of high-resolution nerve ultrasound in a dynamic setting predominate. The MR neurography is indicated here, especially in the frequent bottleneck syndromes and only in very isolated and selected cases.

CONCLUSION

In addition to a correct anatomical assignment, the timely decision for a possible intervention and the appropriate concomitant treatment are an important basis for a favorable prognosis of nerve injuries. Imaging techniques should therefore be used early in the diagnostics and follow-up controls of peripheral nerve injuries.

Lumbar plexus safe working zones with lateral lumbar interbody fusion: a systematic review and meta-analysis

PURPOSE

Significant risk of injury to the lumbar plexus and its departing motor and sensory nerves exists with lateral lumbar interbody fusion (LLIF). Several cadaveric and imaging studies have investigated the lumbar plexus position with respect to the vertebral body anteroposterior plane. To date, no systematic review and meta-analysis of the lumbar plexus safe working zones for LLIF has been performed.

METHODS

This systematic review was conducted according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Relevant studies reporting on the position of the lumbar plexus with relation to the vertebral body in the anteroposterior plane were identified from a PubMed database query. Quantitative analysis was performed using Welch's t test.

RESULTS

Eighteen studies were included, encompassing 1005 subjects and 2472 intervertebral levels. Eleven studies used supine magnetic resonance imaging (MRI) with in vivo subjects. Seven studies used cadavers, five of which performed dissection in the left lateral decubitus position. A significant correlation (p < 0.001) existed between anterior lumbar plexus displacement and evaluation with in vivo MRI at all levels between L1-L5 compared with cadaveric measurement. Supine position was also associated with significant (p < 0.001) anterior shift of the lumbar plexus at all levels between L1-L5.

CONCLUSIONS

This is the first comprehensive systematic review and meta-analysis of the lumbar neural components and safe working zones for LLIF. Our analysis suggests that the lumbar plexus is significantly displaced ventrally with the supine compared to lateral decubitus position, and that MRI may overestimate ventral encroachment of lumbar plexus.

Variations of the extrapsoas course of the lumbar plexus with implications for the lateral transpsoas approach to the lumbar spine: a cadaveric study

BACKGROUND

Together with an increased interest in minimally invasive lateral transpsoas approach to the lumbar spine goes a demand for detailed anatomical descriptions of the lumbar plexus. Although definitions of safe zones and essential descriptions of topographical anatomy have been presented in several studies, the existing literature expects standard appearance of the neural structures. Therefore, the aim of this study was to investigate the variability of the extrapsoas portion of the lumbar plexus in regard to the lateral transpsoas approach.

METHODS

A total of 260 lumbar regions from embalmed cadavers were utilized in this study. The specimens were dissected as per protocol and all nerves from the lumbar plexus were morphologically evaluated.

RESULTS

The most common variation of the iliohypogastric and ilioinguinal nerves was fusion of these two nerves (9.6%). Nearly in the half of the cases (48.1%) the genitofemoral nerve left the psoas major muscle already divided into the femoral and genital branches. The lateral femoral cutaneous nerve was the least variable one as it resembled its normal morphology in 95.0% of cases. Regarding the variant origins of the femoral nerve, there was a low formation outside the psoas major muscle in 3.8% of cases. The obturator nerve was not variable at its emergence point but frequently branched (40.4%) before entering the obturator canal. In addition to the proper femoral and obturator nerves, accessory nerves were present in 12.3% and 9.2% of cases, respectively.

CONCLUSION

Nerves of the lumbar plexus frequently show atypical anatomy outside the psoas major muscle. The presented study provides a compendious information source of the possibly encountered neural variations during retroperitoneal access to different segments of the lumbar spine.

Regional Anesthesia for Vascular Surgery and Pain Management

Patients undergoing vascular surgery tend to have significant systemic comorbidities. Vascular surgery itself is also associated with greater cardiac morbidity and overall mortality than other types of noncardiac surgery. Regional anesthesia is amenable as the primary anesthetic technique for vascular surgery or as an adjunct to general anesthesia. When used as the primary anesthetic, regional anesthesia techniques avoid complications associated with general anesthesia in this challenging patient population. In this article, the authors describe regional anesthetic techniques for carotid endarterectomy, arteriovenous fistula creation, lower extremity bypass surgery, and amputation.